In fluid circulation systems such as hydraulic, lubrication and cooling systems, it is desirable to provide facility for detecting presence of particles suspended in the fluid, which might indicate a need for maintenance or repair of the system. For example, in hydraulic transmission systems, it is desirable both to detect presence of metal particles or chips suspended in the fluid, and to remove such particles for preventing damage to the pump or transmission. Conventionally, particle detectors of the subject character are constructed of a mesh or screen woven from stainless steel and polyester filaments. The mesh is cut and formed to the desired shape, often cylindrical, and the ends of the conductive filaments are welded to each other at each end of the shape. The mesh is attached by epoxy or other bonding material to a structural frame, and electrical connection is made to the conductive filaments. When the structural frame is electrically conductive, phenolic or other suitable insulators must be interposed between the mesh and the frame. Conductive particles are detected when they bridge adjacent conductive filaments.
Although the wire mesh-type particle detectors described above have enjoyed commercial acceptance and success, improvements are desirable. In particular, the described particle detectors are difficult and expensive to manufacture, and are often not as robust as desirable for industrial and aircraft applications, for example. It is therefore a general object of the present invention to provide a particle detector of the described character that is inexpensive to manufacture, that is well suited for high-volume production, that is of robust character, and that provides reliable particle detection and filtering over an extended operating life. Another object of the present invention is to provide a method of constructing such a detector.